Apparatus for rolling tubing into a convoluted contour



Aug. 24, 1965 w. H. LEINBACH 3,201 963 APPARATUS FOR ROLLING TUBING INTO A CONVOLUTED CONTOUR Original Filed June 30, 1960 INVENTOR. W/WE/n file/hbacfi BY 4444 w a,

A TTORNE YS United States Patent 3,261,963 APEARATUS 1 0R ROLLHNG TUBING INTO A CUNVULUTED CONTQUR Wiiiiarn H. Leinbaeh, Rte. 3, Hillsrlale, Mich.

Original application dune 3t), 1966, Ser. No. 40,024, now

Patent No. 3,149,512, dated Sept. 22, 1964. Divided and this application Feb. 15, 1963, Ser. No. 258,718

9 fllaims. (Cl. 72-77) in g dies rolling a form on a supported tube.

A further object of the invention is to provide an improved form of mandrel supporting metal tubing for the rolling of forms thereon by rotatably driven rolling dies in which the mandrel cooperates with the dies to form an advancing means for the tubing during the rolling operation.

A still further object of the invention is to provide an improved form of mandrel, forming a support for metal tubing for rolling forms thereon, in which the mandrel has convolutions conforming to the internal pitch diameter of the finished convoluted tubing, forming a support for the tubing, and has convolu-tions formed thereon of the outside pitch diameter of the convolutions of the external pitch diameter of the finished tubing and meshed with the forming dies, to effect the advance of the mandrel and tubing along the dies, during operation thereof.

A still further object of the invention is to provide an improved form of rolling die for rolling convolutions on cylindrical tubing in which the die is so formed as to form the tubing by compressing the tubing along the supporting surfaces of a mandrel.

Still another object of the invention is to provide an improved form of die having helical convoluti-ons thereon progressively increasing in depth to the form of the final I convolutions of the finished form, for rolling forms such as threads, fins, splines and the like in tubing.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

FIGURE 1 is a diagrammatic end view generally illustrating a set of rolling dies, rolling a form on a tubular blank supported on a mandrel constructed in accordance with the principles of the present invention;

FIGURE 2 is an enlarged view of a form of mandrel constructed in accordance with the principles of the present invention, showing a tubular blank supported on the mandrel, in broken lines;

FIGURE 3 is a fragmentary diagrammatic sectional view showing a rolling die rolling threads on a tubular blank supported on a mandrel constructed in accordance with the principles of the present invention.

In the embodiment of the invention illustrated in F1 URES 1, 2 and 3 of the drawings, I have shown in FIG- URE 1 a tubular blank 16 supported on a mandrel 11 and have shown three roller dies 12 for rolling a form, such as a thread on the tubular blank It].

The tubular blank 18 may be made from any suitable material such as steel, aluminum, brass, copper or any other material that may be rolled. The external or outer diameter of the tubular blank is greater than the outer diameter of the finished form and the blank should have a wall thickness containing sufficient volume, that will leave 3,201,953 Patented Aug. 24, 1965 a finished wall of a desired thickness, without loss or waste of material, when the blank is worked.

The rolls 12 are generally cylindrical in form and may be mounted on and driven from a cylindrical die machine, an automatic screw machine, a turret lathe or like machine in a manner well known to those skilled in the art, so not herein shown or described.

'It should be understood, however, that while I have shown three cylindrical dies that I may also use one or two cylindrical dies and that the dies need not be cylindrical and may be flat or planetary thread rolling dies, if desired.

The mandrel 11, as shown in FIGURE 2, has a forward or advance end portion 13 forming an initial feeding portion of the mandrel. The feeding portion 13 is threaded or helically convoluted to conform to the external pitch diameter of the finished threads or convolutions to be formed on the tube. The threads or convolutions of the advance end portion 13 of the mandrel are meshed with threads of the cylindrical dies 12, and feed the tubular blank and mandrel to enter the dies 12 during rotation of the dies, it being understood that working on the blank by the rotating dies effects rotation and. axial movement of the blank and mandrel through the dies. The threaded end portion 13 terminates at its inner end in a shoulder 15 adapted to be abutted by the end of the tubular blank it when mounted on the mandrel 11, as shown in FIG- URE 2. The portion of the mandrel ll rearwardly of the shoulder 15 forms a support for the tube 11 and is formed to conform to the inside pitch diameter of the finished threads or convoiu-tions to be rolled on the tubular blank it), as diagrammatically shown in FIGURE 3, showing the mandrel 11 with acme threads 21 extending therealong. The form of the threads or convolutions extending along the mandrel, however, may be varied and may be in the form of helical fins or may be of any other desired forms where it is desired to roll various other forms on the tubular blank Ill.

Each die 12 is in the form of a ,roll having a tapered or frusto-conical entrant face 19 extending from a leading wall 14 of the die. The frusto-conical entrant face 19 terminates at its large diameter end into a smooth cylindrical die face 16, of a diameter corresponding to the outer diameter of the crest of the thread to be formed on the tube when the die is in its rolling working position. A thread 17 progressively rises out of the cylindrical die face 16 and extends along the die in a helical path to the trailing end of the die. The thread 17, as it rises out of the die face 16, initially has flanks 17a extending parallel to flanks 21a of the thread of the mandrel. The flanks 17a are relatively short compared to the depth of the thread 21 and are connected by a concave face or crest 24. The concave crest 24 extends along the thread until the thread approaches the maximum desired height, as indicated by reference character 18. The concave portion 24 provides relief for the thread of the die and directs the initial points of pressure to the flanks 17a of the thread of the die, rather than on the ultimate root of the tooth of the thread, and enables the flanks to be formed in the blank against the flanks of the mandrel and to be reduced to a uniform thickness prior to forming the root of the blank by the crest of the completed thread 18 of the die.

In carrying out the operation of rolling threads on a cylindrical tube, a tubular blank having an outside blank diameter larger than the measured diameter of the form to be imparted on the tubing is placed on the mandrel 11 with an outer end thereof in abutting engagement with the shoulder 15. The mandrel and the tube being suitably supported, the threaded portion 13 of the mandrel is threaded between the dies 12, the threads 18 of which are of the pitch diameter of the threads to be I the mandrel. x, The entrant face 19 of the cylindrical die 12'thus'ap-;

' a 1 of the tubular blank agamst the Crest of the m n J and an abutment shoulder atithe juncture of said threaded portions adapted to'be engaged'by the end of the tubing formed 'on the tubular blank 19. The cylindrical dies are then rotatably driven and the mandrel and blank are fed axially between said dies by the lead of the threads of the threaded end portion; 13 meshing with the threads of-therotat'ing dies. The frusto conical entrant face 19 will then initially come into rolling engagement with'the leading end of, the: tube in'engagernentwith the departing from the 7 thereof; shoulder and will'thin the wall of theiblank along V the crest of the mandrel '11'until the thickness of the wall of the blank has been reduced to therequir'edthicke ness of the wall of the crest of the c'ompleted piece. The

metal is thus thinned along the-crest of th'e threads of j and during this thinning" operation'any surplus metal is progressively flowed ahead of the contact pointsof the metal with the crest 20 of the thread 21' of the mandrel, into the unfilled spaces between the convolutions of the 7 thread on the mandrel as indicated-by 25, 26 and 21 in FIGURE 3;.

As the blank is being thinned" to reference numerals on the crest and downwardly, along the flanks ofpthe thread, to a pointwher e the downward flow of metal,

along theflanks is restricted by the root rate threadon plies initial pressure to first form the crest of the thread the thicknessfofthe a, crest of the finished thread," the surplus metal is' flowed I r or compressed into the cavity between the convolutions of the thread of the mandrel ahead of the'contact points, r

a a. While I have herein shown and;desc ribed one form in which my invention maybe embodied, it should be "understood that I do not desire to limit the invention to the specific form shown, but that; various variations and modifications in the invention may be attained without spirit and scope of the novel-conceptsv I claim as inventionz i I ;1. IAfmandre'l for supporting tubing for mung the tub-.

ing, into a convoluted. contour comprising a first convolutedqma'ndrel portion having 1 a pitch diameter equal to the internal pitch=diameter of the finished convolutions on the tubing and havinga second convoluted portion extending-from said first mentionedbonvoluted portion andhaving a pitch diameter equal: to the external pitch diameter of the finished form and of a larger pitch rdiam- 'eter than the pitch'diameter of the first convoluted man- 'drel' portion. i

(21' A mandrel for. supportingf tubing for rolling con- 20,

,7 portion extending for a greater portion of the length of the voluted forms thereon comprising a first threaded mandrel mandrel and forming a support forthetubing and having convolutions formed thereon of a pitch diameter-equal portion; extending from said first convoluted portion to r the advance end, of said n andrelhavin'g a pitch diameter equal to the external pitch diameter of the convolutions to the desired thickness,'- while the die surfacelfi between 1 convolutions of the thread'17jo'f the die, contains any I upward action of themetal atrthe time of compressing the 'metal against the crest of the mandrel. The cylin-l I drical die surface 16 of the dielbetween the teeth 17,f thus forces the metal, reduced from the crest to' flow inwardly into the cavity of the, mandrel between the convolutions of thread 21 thereof; As the rolling op era; j tion is continued, the; die l2 continues "to; contain'the' metal from any upward action, while themandrel 11 supports the metal at all points during wo rking thereof, as the'fianks ofthe teeth on the blank are worked'a'gainst t the flanks of the teeth of the mandrel During this work'- 5 ing operation; the concave portions" 24 {and the crestsj of the threads 17 'of the cylindricalfdie assureithat the of the finished tubing and of alarger pitchdiarneter than the pitchdiarneter ofsaid first threaded mandrel portion,

7 on the first threaded portion.

t threadedtmandrel portion threadedfor a greater portion of the length of the mandrel, the threadsof which have a a pitch diameter equal to theinternal' pitch diameter of the f finished threads formed on the, tubing and having an ininitial points of forming pressure are directed ,by the fianks'17a against the flanks of, the thread of the mandrel,

, rather than on the ultimate root of the thread, untillthe thread approaches its finished form. v

It should here be noted that as the blank jis'formed,

the rolliiig dies meshing with the threaded 'portion713 of, the mandrel and thethreads formed in' -the tubing by the dies, maintainthe tubing in engagementr'withthe shoulder 15 and advance the'mandrel and tubing thereon through the dies.'

It'should further beunderstood that. inia tube rollin'g'l operation byfcylindrical dies, where threads arerolledalong the exteriorl of a tubular; blank on'the'gma'ndrel, that the rolling operation may be a cor tinuous "operation i and that thetubular 'blanh and mandrel mayi be fed 7 through thejroll's .by the rolling action of the' dies andji, threads. may be formed on the'ltube' for the full" length} 5;

thereof, Upon completion 7' of the; thread rolling gopera-i tion, the form'ed'tubular blanl; may then-by unscrewedf from thelinandret11 r ternal feedingjportion extending from said tubing sup- "porting portion and having a diameter equal to the, externalzdi'ameter'of the'finished form and a shoulder at a juncture of saidtube supporting portion with said feeding a portion abuttedby' theend offtheltube vand efiecting ad- ,vance'ofthe tube along the dies upona rollingoperation.

, vfl. Atroller die for reducing metal tubing'andflowing the tubing to'conform to' a selected form comprising a j roll having a generally cylindrical root surface having at 4 least one'helical"convolutionextending therealong from onetend to the other, of the die and rising from the cylindrical root surfaceiof said die in a spiral path to the height a of the finished form, saidconvolution havinga crest of a concave form for-a portion of the length of the convolution and conforming to the root'of'thefinished form for the balance of' thelength of the'convolution.

t 5. A roller die for reducing metal tubing'by compressing the wall of the tubing and forming the tubing to conform to the ferrnv of a'mandr'el, comprising a roll having a leading endwall having a frustofconical-entrant face diverging' fror n said wall and terminating into a smooth cylindrical die face and of a diameter'corresponding to 'thejoutsidej' diameterpf-the crest-:ofthe thread to be formed,xand a thread progressively rising outof said cylindricalldie face and extending alongv the tperiphery of the die ifl ahelicalrpathlto the trailing end'of the die.

6. An apparatus for rolling threads andthe like on tubing comprising a mandrel-supported for rotation'and' for: movement-along itsflongitudinal' axis, a plurality of 'dies spaced about said mandrel and rotatably .driven to roll threads on a tube on s aid mandrel, said inandrelhavingfa tubef supporting portion having} first threads extend ing'therealong of a fixeddiametersubstantially equal to the inter'nalgpitch diameter of the threadsto :be formed h t'a iirai 'lava e ea a tw n a h advance end thereof and forming a continuation of said tube supporting portion and having threads extending therealong of a pitch diameter greater than the pitch diameter of the first threads and equal to the external pitch diameter of the threads of the finished form, said last mentioned threads on said feeding portion meshing with said dies to effect the advance of the mandrel and tube through said dies to form threads thereon upon rotation of said dies.

7. An apparatus for rolling threads and the like on tubing comprising a mandrel supported for rotation and for movement along its longitudinal axis, a plurality of dies spaced about said mandrel and rotatably driven to roll threads on a tube on said mandrel, said mandrel having a tube supporting portion having threads extending therealong of a pitch diameter substantially equal to the internal pitch diameter of the threads formed on the tubing, and having a feeding portion at the advance end thereof and forming a continuation of said tube supporting portion and having threads extending therealong of a pitch diameter equal to the external pitch diameter of the threads of the finished form, said last mentioned threads on said feeding portion meshing with said dies to effect the advance of the mandrel and tube through said dies toform threads thereon upon rotation of said dies, and a shoulder at the junction of said tube supporting portion with said feeding portion of said mandrel, engaged by the leading end of the tube during the rolling of threads thereon.

8. An apparatus for rolling threads and the like on tubing comprising a mandrel supported for free rotation and for movement along its axis, a plurality of rotating rigidly backed forming dies, each having an entrant frustoeter equal to the internal pitch diameter of the finished form, and having second threads extending therealong of a pitch diameter greater than the pitch diameter of the threads of the first tube supporting surface and of a pitch diameter substantially equal to the external pitch diameter of the threads of the finished form, and said surfaces of said dies meshing with said feeding surface of said mandrel so interacting with said mandrel as to draw the tube and mandrel therebetween to effect the advance thereof and to apply rolling Working pressure on the tube to form the tube to a tubular form.

9. An apparatus for rolling threads and the like on tubing comprising a mandrel supported for free rotation and for movement along its axis, a plurality of rotating rigidly backed forming dies, each having an entrant frustoconical surface for initial contact with a tube on said mandrel, merging into 'a smooth cylindrical surface that progressively changes into the full complement of the desired contour, said mandrel having a threaded tube supporting surface, the threads of which are formed to the pitch diameter of the internal pitch diameter of the finished form and having a threaded feeding surface extending in advance of said tube supporting surface, and having threads extending therealong of a pitch diameter substantially equal to the external pitch diameter of the threads of the finished form, a shoulder at the juncture of said tube supporting surface with said feeding surface abutted by the leading end of the tube, and said first and second surfaces of said dies so interacting with said feeding surface and the tube as to maintain the tube into engagement with the shoulder and draw the tube through the dies to efiect the advance of the tube and said mandrel through said dies and to apply rolling working pressures along successive increments of said tube supported on said mandrel.

References Cited by the Examiner UNITED STATES PATENTS 414,767 11/89 Fox 80-413 498,582 5/93 Sheldon 8O9 2,690,089 9/54 Bedker 806 2,787,796 4/57 Rosan 80-13 FOREIGN PATENTS 37,839 3/32 Holland.

CHARLES W. LANHAM, Primary Examiner.

MICHAEL V. BRINDISI, Examiner. 

1. A MANDREL FOR SUPPORTING TUBING FOR ROLLING THE TUBING INTO A CONVOLUTED CONTOUR COMPRISING A FIRST CONVOLUTED MANDREL PORTION HAVING A PITCH DIAMETER EQUAL TO THE INTERNAL PITCH DIAMETER OF THE FINISHED CONVOLUTIONS ON THE TUBING AND HAVING A SECOND CONVOLUTED PORTION EXTENDING FROM SAID FIRST MENTIONED CONVOLUTED PORTION AND HAVING A PITCH DIAMETER EQUAL TO THE EXTERNAL PITCH DIAMETER OF THE FINISHED FORM AND OF A LARGER PITCH DIAAMETER THAN THE PITCH DIAMETER OF THE FIRST CONVOLUTED MANDREL PORTION. 